It was noted early in the use of Ultraviolet (“UV”) lamps to treat water potentially containing harmful bacteria and viruses that their outer surfaces became coated by compounds resident in the water. For example, when a UV lamp is submerged in the water while inside a protective quartz sleeve almost all of the UV light enters the water. These types of UV lamps operate with surface temperatures from 40° C. to 800° C. depending upon the type of lamp. The water may contain compounds such as calcium, manganese, iron and the like that may precipitate onto the surface of the quartz sleeve due to the heat created by the lamp housed therein. Such precipitate will prevent the UV light from reaching the water to disinfect it or promote a chemical reaction. If the build up of substances becomes great enough to absorb all the UV light the non-ultraviolet wavelengths produced by the lamps will promote microbial growth on the outer surface of the quartz sleeves. Such a coating on the quartz sleeve requires some type of in-place cleaning system or the isolation and disassembly of the UV unit for manual cleaning. The cleaning of the quartz tubes around the UV lamps has been a major challenge for manufacturers of such equipment. Numerous scrapers, brushes, ultrasonics, in-place acid cleaning, air scouring, and chemicals have been proposed to solve this problem.
Prior art scrapers or wipers typically involve some form of felt, rubber, metal, plastic or Teflon® that is pushed or pulled down the length or around the circumference of a quartz tube. These prior art systems describe different ways of carrying out this process. U.S. Pat. No. 1,998,076 for a scraper was issued to H. M. Creighton et al. in 1935. This scraper is pressed against a quartz sleeve and it was driven by a set of gears with the lamp in the centre. Variations on the wiper of Creighton et al. followed. S. Ellner in 1965 used an external motor with gears to push a scraper down the length of a quartz tube (U.S. Pat. No. 3,182,193) inside a pressurized UV system. J. Czulak et al. in U.S. Pat. No. 3,336,099 described a wiper that was driven along the length of the quartz tube by the flow of water. G. W. Robertson also used the flow of water to drive a floating wiper down the length of a quartz tube. It had fins so that it spun as it moved along the quartz tube. In 1965 A. Young received U.S. Pat. No. 3,462,597 for a wiper system with a plunger to manually push a wiper the length of the single ended quartz tubes. The wiper was made of Teflon®. H. Boehme in 1990 was granted U.S. Pat. No. 4,922,114 for almost an identical system. In 1965 D. E. Wiltrout was issued U.S. Pat. No. 3,566,105 for an hydraulic means to push the wiper along the length of a quartz tube. A. F. McFarland et al; (U.S. Pat. No. 3,182,191 in 1965); R. W. Hippen (U.S. Pat. No. 3,562,520 in 1971); and D. G. Hagger and R. L. Petersen (U.S. Pat. No. 5,227,140 in 1993) used a spring to return a wiper to the resting position when the water ceased to flow. M. D. Wood in U.S. Pat. No. 4,367,410 expanded on the idea of a wiper when he cleaned the entire UV array with one assembly. See, e.g., FIG. 3 of that patent. This system was not successful due to tolerance problems that resulted in breakage of the quartz sleeves. U.S. Pat. No. 5,528,044 was issued to J. A. Hutchison in 1996 for a wiper that was made from flat pieces of very thin metal (FIG. 1 of that patent). The inner circumference of the wiper had small cuts in it so that the wiper would flex as it moved along the quartz tube.
R. L. Peterson was issued U.S. Pat. No. 5,501,843 in 1996 for a wiper that used a cartridge full of stainless steel filings or stainless steel wool (FIG. 6 of that patent).
Patents have been issued for using ultrasonics for cleaning quartz sleeves in pressurized UV systems (R. M. G. Boucher U.S. Pat. No. 3,672,823, E. A. Pedziwiatr U.S. Pat. No. 4,728,368, and J. M. Maarschalkerweerd U.S. Pat. No. 5,539,209); semi-pressurized UV systems (S. Ellner U.S. Pat. No. 4,358,204); and UV probes (J. M. Maarschalkerweerd U.S. Pat. No. 5,539,210). Ultrasonic systems that were used to clean UV systems for wastewater were not effective (United States Environmental Protection Agency, 1986).
U.S. Pat. No. 5,133,945 was issued to Hallett et al. in 1992 for using a brush to clean quartz sleeves in a pressurized UV system. In 1993 a German design Patent DE3710250 was issued to W. Stellrecht et al. for using a brush to clean quartz sleeves and the inner surface of a pressurized UV unit.
S. Ellner was issued U.S. Pat. Nos. 4,103,167, 4,899,056 and Re34,513 in 1978, 1990, and 1994 respectively for using an acid to clean quartz sleeves either in-place with a recirculation system or after lifting the UV modules out of a channel. All of these methods required that the UV system be taken out of service. P. Binot was issued U.S. Pat. No. 5,725,757 in 1998 for use of an acid and air injection system to clean a pressurized UV system.
P. Schuerch et al. was issued U.S. Pat. No. 5,332,388 in 1994 for an air scouring system for a vertical lamp UV system used for disinfecting wastewater.
J. M. Maarschalkerweerd was issued U.S. Pat. No. 5,418,370 in 1995 for a chemical and mechanical method for cleaning the quartz sleeves in a semi-pressurized UV system. The quartz sleeve contracts into a sleeve and the acid inside the sleeve dissolves any minerals and the seals at the front of the sleeve scrape off any deposits. This cleaning system was modified so that the sleeve moved along the quartz sleeve. E. Ishiyama invented a chemical and mechanical method for cleaning the quartz sleeves in an open channel parallel flow UV system with horizontal lamps and was issued U.S. Pat. No. 5,874,740 in 1999. The acid cleaner needs to be continually replenished.
On Aug. 13, 2002 U.S. Pat. No. 6,432,213B2 was issued to Wang and Sotirakos for a scraper (See FIG. 1 of the patent) for removing deposits from the exterior of a tubular member which included elements that defined an outer jacket which has an inwardly open circumferential recess and two aligned axial openings, and a scraper element in the form of an elongate non-round resilient wire bent to define a series of integral concatenated, resilient segments, each pair of adjacent segments being connected through a bend or geniculation. This scraper is expensive to make because the outer jacket must be precisely machined. Moreover, while this scraper is very effective, it is prone to clogging inside the outer jacket with organic material, sand and other materials when it is used on the quartz sleeves of a UV system treating wastewater. Examples of UV systems that could use this scraper are shown in U.S. Pat. Nos. 5,006,244, 4,482,809, 4,757,205, and 6,231,820B1. As the flow of wastewater is parallel to the lamps in these UV systems and perpendicular to the scraper debris is captured by the wires of the scraper and this debris is not flushed out due to the closed circumference of the scraper. This debris or sand eventually compacts inside the outer jacket formed by the closed circumference because of the scrapping action and prevents the scraper from working.
Accordingly, it is an object of the present invention to provide a scraper which utilizes the advantages of the resilient wire geniculated segments of U.S. Pat. No. 6,432,213B2, but without the disadvantages inherent therein. It is a further object of the invention to provide an effective scraper for UV quartz housings which is relatively inexpensive to manufacture.